Minimum displacement balanced control valve



March 10, 1959 I s. D. POOL ETAL 2,876,796

MINIMUM DISPLACEMENT BALANCED CONTROL VALVE Filed Nov. 12. 1954 2Sheets-Shet 1 cry/m5? A Hui q; cm ma 3 Z;z1/e nfor5: faarl D. Pool v{award Melz'n Mo. "an-ra March 10, 1959 s. D. POOL ETAL 2,876,796

- MINIMUM DISPLACEMENT BALANCED CONTROL VALVE Filed Nov. 12 1954 2Sheets-Sheet 2 J8 U A 14 nyvENToRs ggzzrazz fire! United States atentMINIMUM DISPLACEMENT BALANCED CONTROL VALVE Stuart D. Pool, Moline, andEdward Island, 111., assignors to International pany, a corporation ofNew Jersey Application November 12, 1954, Serial No. 468,302 7 Claims.(Cl. 137-622) M. Melin, Rock Harvester Zom- This invention relates to anew and improved control valve.

The operation of much present day equipment and apparatus is beingperformed by hydraulic mechanisms for the reason that hydraulics lendsitself to remote positioning and efliciency of operation. The search forcontrol valves of a type to efliciently direct fluid to varioushydraulic control units has been unending.

It is, therefore, a principal object of the present invention to providea control valve for effecting the efficient and easy directing of fluidunder pressure to various hydraulic mechanisms.

An important object of this invention is the provision of a controlvalve for hydraulic systems wherein the valve has a balancedconstruction in which there is no back pressure to aifect or throw thevalve at any position of the valve spool.

A still further important object of this invention is to supply acontrol valve for hydraulic mechanisms in which the movement of theactuating portion of the valve is relatively small.

Another and still further important object and advantage of thisinvention is to provide a control valve for hydraulic systems in which asliding spool is employed and wherein no position of the spool willentirely block flow of fluid into or out of the valve.

A still further important object of this invention is the provision of acontrol valve for the operation of hydraulic apparatus and wherein thecontrol valve may be used in series or tandem.

Another important object of this invention is to provide a control valvewith a sliding spool having symmetrical lands about the center andslidable within a housing having symmetrical lands about a center.

Other and further objects and advantages of this invention will becomeapparent from the disclosures in the following specification andaccompanying drawing.

In the drawing:

Fig. 1 shows a transverse sectional view taken through the control valveof this invention and having representative cylinders to be operatedshown in association therewith.

Fig. 2 is a sectional view of the valve as shown in Fig. 1 but havingthe spool thereof moved toward one end.

Fig. 3 is another sectional view of the valve as shown in Figs. 1 and 2but with the spool moved to the other end.

As shown in the drawing, the reference numeral indicates generally ahousing for the valve which is provided with a longitudinally extendingbore 11 within which a spool or slide valve member 12 is slidablypositioned. The housing 10 is provided with an inlet 13 and an exhaustoutlet 14. Fluid under pressure is delivered to the inlet 13 in thehousing and fluid may be removed from the housing through the exhaustport 14. A longitudinally extending passage 15 is positioned in thehousing and lies parallel to the central bore 11. This passage 15 is inassociation with the inlet port 13 and receives fluid under pressurefrom the inlet 13. Radial passages 16, 17 and 18 communicate with thepassage 15 and the central bore 11 at both ends and at the center of thespool 12. It is thus evident that as fluid under pressure is deliveredto the control valve through the inlet port 13 this fluid will bedispersed through the passage 15 and thereafter delivered radiallyinwardly through the passages 16, 17 and 18 to the central bore 11wherein the fluid is diverted as desired by means of the spool or slidevalve 12. It is this symmetrical feeding of fluid to both ends and thecenter simultaneously that contributes to the short stroke and the lackof resistance to movement of the operating spool.

A second longitudinally extending passage 19 is positioned in thehousing 10 and lies parallel to the central bore 11 and spaced apartfrom the longitudinally extending passage 15. Here again radial passages20, 21 and 22 join the longitudinally extending passage 19 and thecentral bore 11. In the same manner that the passage 15 joins with theinlet port 13 the passage 19 forms an integral part of the exhaust port14, thus providing for communication of the central bore 11 with theexhaust port 14 at the spaced points of the radial passages 20, 21 and22.

The spool 12 is equipped with a centrally disposed an nular groove 23which in the position of the device as shown in the drawing permitspassage of fluid from the inlet 13 through the passage 15, through thepassage 18, around the annular groove 23, and thence to the radialpassage 22 leading to the longitudinally disposed passage 19. However, aspring retained ball valve 24 is adapted to engage a seat 24a within thepassage 22. The ball valve 24 is urged toward closed position againstthe seat 24a by means of a coil spring 25. The spring 25 may be of anydesired strength and the ball 24 and spring 25 combine to provide a.relief or by-pass for the control valve in the event some predeterminedpressure is exceeded, whereafter fluid may be by-passed from the inletof the control valve directly to the exhaust of the control valve.

The spool valve 12 further includes a plurality of alternate annularlands and annular grooves spaced outwardly and symmetrically from thecentral annular groove 23 as follows: Spaced apart annular lands 26, 27and 28 on one side of the annular groove 23 and spaced apart annularlands 29, 30 and 31 on the other side of the central annular groove 23.Intermediate the annular lands 26, 27 and 28 on the one side of thespool are annular grooves 32 and 33, and similarly on the other sidebetween the annular lands 29, 30 and 31 are annular grooves 34 and 35.The central bore 11 of the valve housing 10 is provided with spacedapart internal annular grooves or recesses 36, 37, 38, 39, 40 and 41.The width of the annular lands and annular grooves are all substantiallythe same except for the central annular groove 23 which is considerablywider.

In order to complete the description of the construction of the spool orslide member 12, it should also be explained that the spool has acentral passage 42 and spaced apart radial passages 43 and 44 which thusjoin the spaced annular grooves 32 and 33. Similarly, another centralpassage 45 spaced longitudinally apart from the passage 42 adjoinsradial passages 46 and 47 to thereupon permit fiuid communicationbetween the annular grooves 34 and 35. I

The outlets for the cylinders A and B are shown in the drawing at 48 and49. These ports 48 and 49 are located within the housing 10 at theposition of the spaced lands 26 and 29 in the spool 12 when that spoolis centered within the housing as shown in the'drawing. The slide spoolvalve 12 is provided with a laterally extending portion 50 projectingfrom one end of the housing 10 and 3 has a transverse opening 51 in theouter end thereof for actuation of the slide valve by a manual pushingand/or pulling in the direction of the arrow 52 for filling the cylinderA with fluid and exhausting fluid from the cylinder B and moving theslide valve in the direction of the arrow 53 in order to direct fluidunder pressure to the cylinder B and exhaust fluid from cylinder A.Obviously movements of the slide valve 12 perform the function ofoppositely extending and/ or retracting piston rods 54 and 55 projectingdownwardly from cylinder A as shown at 56 and from cylinder B as shownat 57, respectively. A flexible conduit 53 joins the port 48 with thecylinder A and similarly a flexible conduit '59 joins the port 49 withthe cylinder B. The cylinders A and B are joined at their lower ends byconduit 60. Thus when fluid under pressure is delivered to the conduit58 the piston rod 54 from cylinder A is extended and simultaneouslyfluid under pressure is delivered to the lower end of the cylinder B,causing the piston rod 55 to be retracted. Conversely when .fluid underpressure is delivered to the conduit 59 piston rod 55 is extended andpiston rod 54 is retracted.

Although two cylinders have been shown in series or tandem connectionfor operation by the control valve of this invention, it should beunderstood that merely one hydraulic cylinder may be operated by thecontrol valve wherein fluid under pressure is delivered to either thetop or bottom of the one cylinder whereupon the piston rod will beeither extended or retracted. Or, it is entirely possible that more thantwo cylinders may be operated by this single control valve.

It should be noted that the radial passages 16 and 17 feed fluid fromthe inlet 13 to the endmost internal annular recesses 36 and 41 and thatthe radial passages 20 and 21 receive fluid from the penultimateinternal annular recesses 37 and 40 at each end of the housing bore. Theports 48 and 49 for delivering to or receiving fluid from the cylindersA and B are joined to the innermost internal annular recesses 39 and 38respectively of the housing bore.

The spool 12 has symmetrical annular grooves 65 and 66 in the end lands28 and 31 for the purpose of receiving sealing rings 67 and 68respectively. The sealing rings permit sliding of the spool within thehousing bore without permitting escape of fluids endwise from thecontrol valve.

In the operation of the control valve of this invention the centeredposition of the spool 12, as shown in the drawing, permits fluid underpressure to be uniformly exhausted about the symmetrical ends of thevalve. At one end the fluid is delivered from the inlet 13 to the radialpassage 16 and thence to the exhaust port 14 by reason of the slightoverlapping of the annular recess 36 in the housing communicating withthe annular groove 33 in the spool 12 which engages by a similar slightoverlapping the annular recess 37 in the housing 10. The radial passage20 leading to the exhaust port 14 is in com munication with the annularrecess 37 and thus fluid is directly discharged from the inlet to theexhaust. Similarly fluid under pressure delivered to the inlet 13 issimultaneously permitted passage through the radial conduit 17 at theother end of the valve forcommunication with the annular recess 41 inthe housing 10. A slight overlapping of the annular recess 41 with theannular groove 35 in the spool 12 provides for passage of the fluid tothat annular channel 35 and thence by reason of a further and similarslight overlapping with the internal annular groove or recess 41) in thehousing 10 fluid reaches that recess. The radial passage 21 is in directcommunication with the annular groove 40 and thus carries fluid from theinlet 13 to the longitudinally extending passage 19 and thence outwardlythrough the exhaust port 14. The pressures on both ends of thesymmetrically designed control valve of this invention are thus balancedso the spool or slide valve 12 may beeasily manually moved savanna fromone position to another to efiect shifting of the direction of fluidthrough thp control valve. The entire movement of the control. valvespool 12 is relatively minute and yet it accomplishes all of the variousfunctions of the valve. It will be seen that the overlapping of theannular grooves in the spool 12 with certain of the internal annularrecesses in the housing 10 is relatively slight making it necessary onlyto move the slide valve a relatively short distance whereuponcommunication between the recesses is made larger or cut ofl entirelydepending upon the direction of movement of the spool 12.

Let us assume, for example, that the spool 12 is moved in a leftwarddirection as viewed in Figure 2 of the drawing and as shown by the arrow52 in Figure 1. Overall movement of the spool 12 is relatively slight.This slight movement is in the order of one to two hundredths of aninch. When this movement of the spool valve occurs in the direction ofthe arrow 52, and as shown in Figure 2 the land 28 on the spool bars theadmission of incoming fluid under pressure from the inlet 13 to theannular groove 33 in the spool. However, the other end of the controlvalve is merely opened a greater amount whereupon fluid is admitted tothe annular groove 35, but here again the land 36 bars admission of thisincoming fluid to the annular groove 40 in the housing so that theincoming fluid does not reach the exhaust port 14 from either end.Incoming fluid is also simultaneously delivered to the centrallydisposed radial passage 18 whereupon this fluid enters the wide annulargroove 23 in the slide valve 12 whereafter it communicates directly withthe annular recess 39 disposed internally of the housing for admissionof the fluid to the cylinder A. Thus there is an extension of the pistonrod 54 of cylinder A when the spool 12 is moved to its position as shownin Figure 2. Simultaneously with the admission of fluid under pressureto the cylinder A there is an exhausting of fluid from cylinder Bthrough the conduit 59 to the port 49 through the internal annularrecess 38 in the housing which now communicates directly with theannular groove 32 in the spool 12. Thus by reason of the radial andcentral passages 43, 42 and 44 fluid from the cylinders is dischargedthrough the annular groove 37 in the housing to the exhaust port 14.

Conversely when the spool 12 moves in a rightward direction, asindicated by the arrow 53 in Figure 1 and as shown in Figure 3 of thedrawing, fluid under pressure from the inlet 13 of the control valve isdelivered to the top of the cylinder B through the flexible conduit 59and exhausted by retracting of the piston rod '54 in the cylinder A andthence backwardly through the flexible conduit 58 to the control valveand thereafter out the exhaust port 14 in the same manner as describedfor the other movement of the control valve.

It is apparent that herein is provided a control valve for cylinders ofthe hydraulic type to be operated and that such control valve operateswith a balanced construction wherein there is no back pressure on eitherside which might affect the throw of the valve spool as in ordinarycontrol valves. Further, the movement of the spool valve need only berelatively minute to accomplish the changes in direction of the flow offluid under pressure and/or the movement of the control valve to theneutral position wherein fluid is continuously exhausted directed fromthe inlet port to the exhaust port. Obviously there are manyapplications for a control valve of this type and it is applicantsintention to inelude all of the possible uses to which the controt valvemay be put as well as the mechanical construction of the valve which maybe changed in detail Without departing from the principles disclosedherein and we, therefore, do not propose limiting the patent grantedhereon otherwise than as necessitated by the appended claims.

What is claimed is:

1. A control valve comprising a housing, said housing having anelongated bore, a spool slidably mounted in said bore, said spool havinga plurality of alternately spaced annular lands and annular groovessymmetrical about a center line, said elongated bore of the housinghaving a plurality of spaced apart internal annular recesses symmetricalabout a center line and each of said spaced apart internal annularrecesses in the bore of said housing disposed substantially opposite oneof the spaced annular lands on said spool when the spool is centeredwithin said housing, said communicating with both of the endmostinternal annular recesses of the elongated bore, said housing having anexhaust outlet simultaneously communicating with the penultimateinternal annular recesses at each end of the elongated bore, saidhousing having separate ports joining with the two innermost internalannular recesses, said spool having spaced apart central passages andradial passages communicating with the central passages at the positionsof the endmost and the penultimate annular grooves of each end of thespool, said spool in its centered position in said housing having itsouter and penultimate annular lands slightly open with respect to theouter and penultimate annular recesses in the housing at both endsthereof, and means for slidably moving said spool within said bore.

housing having an inlet simultaneously 2. A device as set forth in claim1 in which the annular 25 grooves of the spool are substantially thesame width as the internal annular recesses of the elongated bore.

3. A device as set forth in claim 1 in which said inlet includes saidhousing having a passage therein disposed parallel to said bore andadjoining radial passages at spaced positions in alignment with theendmost internal annular recesses.

4. A device as set forth in claim 1 in which said exhaust outletincludes said housing having a passage therein disposed parallel to saidbore and adjoining radial passages at spaced positions in alignment withthe penultimate internal annular recesses at both ends of the housing.

5. A device as set forth in claim 3 in which said exhaust outletincludes said housing having a second passage therein disposed parallelto said bore and adjoining radial passages at spaced positions inalignment with the penultimate internal annular recesses at both ends ofthe housing.

6. A device as set forth in claim has a centrally disposed annulargroove between the innermost annular lands, a radial passage in saidhousing communicating between the passage therein and the centralannular groove of the spool, a second radial passage in said housingcommunicating between the second passage and the central annular grooveof the spool, and pressure relief valve means disposed in said secondradial passage.

7. A device as set forth in claim 6 in which said central annular grooveis wider than the other annular grooves of the spool.

References Cited in the file of this patent UNITED STATES PATENTS 5 inwhich the spool 2,331,108 De Ganahl Oct. 5, 1943 2,486,087 Wright Oct.25, 1949 2,600,746 Ernst June 17, 1952 2,636,566 Jedrziewski Apr. 28,1953

